Refrigerating machine



N 0 mm H m 1 A W L BEFRIGERATING MACHINE Original Filed Dec. 1, 1937 Inventor: Leonard W. Atchis His Attorney.

Patented Mar. 11, 1941 UNITED STATES REFRIGERATING MACHINE Leonard W. Atchison, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application December 1, 1937, Serial No. 177,521 Renewed February 8, 1940 10 Claims. (Cl. 62-116) My invention relates to refrigerating machines, and particularly to refrigerating machines having a plurality of evaporators maintained at different refrigerating pressures.

In order to provide household refrigerator cabinets or other spaces to be cooled with two or more temperature zones, a plurality of evaporators may be provided in the circuit of a re frigerating machine in such a manner that they may be operated at different pressures and, therefore, at different temperatures. A plurality of evaporators may be connected in series in the refrigerant circuit of a refrigerating machine so that the second evaporator receives. refrigerant In from the first evaporator and so on. The relative temperature of any two evaporators may then be regulated by controlling the rate of flow of refrigerant from the first of the evaporators to the second. Accordingly, it is an object of my in- 20 vention to provide a refrigerating machine having a plurality of evaporators and an improved arrangement for maintaining different temperatures in said evaporator-s and for controlling thedistribution of refrigerant to the evaporators.

215 Further objects and advantages of my invention will become apparent as the following description proceeds, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to 30 and forming a part of this specification.

For a better understanding of my invention. reference may be had to the accompanyingdrawing in which Fig. 1 shows a household refrigerating machine provided with a cooling unit com-'- 35 prising a plurality of evaporators and embodying my invention; Fig. 2 shows an enlarged perspective view of the cooling unit shown in Fig.1 with the doors thereof removed and with the control panel moved forward to a position in front of'its 40 normal position in order more clearly to show the construction; Fig. 3 is a view of the inner evaporator shown in Fig. 2 in its form in the flat prior to bending; Fig. 4 is an enlarged sectional plan view of the control valve and dis- 45 tributing device of the cooling unit shown. in

Fig. 2; and Fig. 5 is an enlarged sectional elevation view of the distributing device shown in Fig. 2.

Referring now to the drawing, in Fig. l I have 50 shown a household refrigerating machine including a cabinet 10 having a door II for closing a food compartment l2. A cooling unit i3 supported from the removable top of the cabinet is arranged within the cooling compartment I2 55 to cool the compartment. The cooling unit I3 is connected in the refrigerant circuit of a refrigerating machine comprising a motor and a compressor arranged within a casing M, a condenser |5 surrounding the casing M, and a receiver or float valve chamber l6 mounted on the 5 removabletop of the cabinet. During the operation of the refrigerating machine, refrigerant is compressed by the compressor in the casing M and. is discharged into the condenser I5 where it is cooled and liquefied by radiation and by the air circulating over the condenser by natural convection. The liquid refrigerant flows from the condenser through a connection I! into the float chamber Iii and when a predetermined amount of liquid refrigerant has collected, a float in the chamber rises and the liquid refrigerant flows through a liquid line i8 into the cooling unit [3. The liquid refrigerant in the cooling unit I3 is vaporized by the absorption of heat fromthe air within the cabinet and from articles placed within the cooling unit and the vaporized refrigerant is withdrawn from the cooling unit through a suction line H! and returned to the casing l4 from which it is drawn by the compressor therein. The operation of the compressor is regulated by a control device 20 having a thermostatic element ill in heat exchange relation with'the outer relativelyhigh temperature wall of the cooling unit. I

The construction of the cooling unit i3 is clear-- ly shown in Fig. 2. This cooling unit is similar to-that described and claimed in a copending application of Christian Steenstrup, Serial No. 177,495, filed December 1, 1937, and assigned to the-same assignee as the present application. I do not herein claim anything described or claimed in the said Steenstrupapplication.

The cooling unit l3 includes an outer housing 22 comprising side and back walls formed from complementary inner and outer metal sheets 23 and 2-4 respectively, and the bottom wall comprising a single sheet 25 connected to the back and side walls. The compartment formed by the housing.22 is separated into an upper and a lower section by a double wall comprising metal sheets 26 and 21'. Each of the side walls is provided with a headerZB formed in the upper portion thereof. which is maintained about half full of liquid refrigerant. The middle header formed in the back wall communicates with the headers 0 in the side walls through passages 29 and 30 providing communication between the headers above and below the liquid level respectively. Each of the walls is provided with upright and transverse refrigerant passages 3i and? respectively, with in which liquid refrigerant is circulated, the upright passages 3| communicating with the headers 28 so that vaporized refrigerant may rise to the headers. The liquid line l8 discharges refrigerant into a manifold;33 which extends along the lower edge of the walls and which communicates with one of the upright passages in each of the walls through ducts 34 and thereby injects refrigerant into the upright passages to produce a circulation of refrigerant through the transverse passages. The range of temperature of the outer walls of the casing is regulated by the control device 20, so that the walls are maintained above the freezing point of water, or are allowed to periodically rise above freezing during at least a portion of the cycle and thereby cool the air within the food. compartment l2 on a defrosting cycle without materially reducing the moisture content thereof, continuous frosting of the evaporator being prevented.

In order' to provide a freezing chamber, a flooded evaporator 35 is provided in the upper portion of the housing. This evaporator as shown in Figs. 2 and 3 comprises a sheet metal structure having formed thereina header 36 and a plurality of U-shaped passages 31 communicating with the header below the normal level of the liquid refrigerant therein. The lower ends of the U-shaped passages 31 are connected by ducts 38 to a manifold 39 and the manifold 39 is ,connected to an inlet passage 40 by a sinuous conduit 4|. Thesheet metal structure, as shown in Fig. 3, is bent into the form shown in Fig. 2, so that the sinuous conduit 4! lies partially in a freezing shelf 42 and partially in a side wall 43 remote from "the header 36. This construction provides a lower freezing compartment completely surrounded" by refrigerant containing walls and an upper compartment formed by the side wall above the shelf 42 and a. wall 44 pro-- viding an extension of the side wall 43. During the operation of the inner evaporator, the sinuous conduit 4! carries all the refrigerant admitted to flooded conduits of the evaporator and this conduit operates as a non-flooded" passage, since it carries a large volume of gaseous refrigerant and a relatively small amount of liquid. The header 36 is normally maintained about half filled with liquid refrigerant, so that the U-shaped passages are maintained flooded. In order to supply refrigerant to the inner evaporator 35, I provide a connection 45 communicating with the header 28 in the rear wall of the outer evaporator. The connection 45 opens into the header near the normal level of liquid refrigerant therein. Therefore, when gaseous refrigerant is withdrawn from the header through the connection, any excess liquid refrigerant is withdrawn therewith. The liquid and gaseous refrigerant flow through the connection 45 to a manually adjustable valve or restricted passage 46 and from the valve to the evaporator l3 through'a connection 41, an upright cylindrical vessel 48, and a connection 49. The connection 49 communicates directly with the passage 40 in the walls of the evaporator 35 below the level of liquid refrigerant therein and produces a circulation of liquid refrigerant by discharging a mixture of liquid and gaseous refrigerant into the circulating passages 31. Gaseous refrigerant collects in the header 36 and is removed therefrom through the suction line Hi. The valve 46 restricts the passage of refrigerant from the outer evaporator to the inner evaporator and thereby maintains a pressure differential between the two evaporators, so

that the inner evaporator operates at a lower temperature than the outer evaporator. The differential of temperature may be varied by adjusting the valve 46. As shown in Fig. 4, the valve 46 comprises a valve stem or plunger 50 which may be moved axially ina valve block 5!. The valve stem 50 is sealed by an expansible bellows 52 and the stem portion may be adjusted by turning a cam 53 which moves the valve stem in opposition to the force of a compression spring 54. A knob 55 is provided to turn the cam 53. A shoulder or stop 56 is provided to limit the closing movement of the valve stem 50, so that the valve can never be closed completely. The cam and valve are mounted in a bracket 51 secured to a panel 58, which is secured to the upper front portion of the cooling unit.

During some periods. of the operation of the cooling unit, a large amount of gaseous refrigerant may be formed in the outer evaporator when there is little or no demand for cooling of the inner evaporator. Furthermore, even when there is demand for cooling of the inner evaporator, the amount of gaseous refrigerant formed in the outer evaporator may be greater than desirable for proper circulation of the refrigerant in the flooded portion of the inner evaporator. A large volume of gaseous refrigerant is particularly undesirable in evaporators provided with series or continuous conduits, such as the sinuous conduit 4!, because the passage of a large volume of gas tends to move the liquid refrigerant quickly through the series conduit and the large volume of gas has little heat absorption capacity and, consequently, freezing loads placed on the series conduit in positions such as on the shelf 42 may not be sufiiciently cooled. In some cases, it is even possible that ice on the shelf might be allowed to melt due to the loss of capacity and the relatively high temperature of the circulating gas. It is, therefore, desirable to reduce the proportion of gaseous refrigerant circulated through the inner or low temperature evaporator. As shown in Fig. 4, the liquid and gaseous refrigerant flowing from the valve 46 enter the upper vessel 48 through the connection 41 near the middle portion thereof and both liquid and gaseous refrigerant flow from the chamber or vessel 48 through the connection 49 to the inner evaporator. In order to remove a portion of the gaseous refrigerant, I provide a restricted duct 59 providing communication between the upper portion of the vessel 48 and the header 36, so that a limited amount of gaseous refrigerant is diverted from circulating through the passage 49 and the series conduit and flooded conduits of the inner evaporator.

The duct 59 is provided, so that the diverted gaseous refrigerant is led directly to the suction line is and withdrawn from the cooling unit without passing through the inner evaporator. By providing the passage 59 for diverting a portion of vaporized refrigerant, the mixture of liquidand gaseous refrigerant, which is conveyed to the inner evaporator, is made to have a greater proportion of liquid refrigerant than would otherwise be possible. Furthermore, since the duct 59 is restricted, there is a substantial pressure drop therein and the pressure drop from the inlet; end of the conduit 40 to the outlet l9 of the inner evaporator is thereby maintained.

The cooling unit is secured to the top wall of the refrigerator cabinet by means of flanges 60 at the tops of the walls and the inner evaporator is secured tothe top wall of the cabinet '62 and 63 respectively as shown in Fig. 1.. These doors prevent the circulation of the cabinet air over the cold portions of the cooling unit and thereby reduce the dehydration of the air and food therein. The lower portion of the compartment is maintained at a temperature intermediate that of the food compartment and that of the freezing compartment.

meats and similar foodstuffs.

During the operation of the refrigerating machine shown in the drawing, the control 20 opcrates to start the refrigerating machine and supply liquid refrigerant to the float chamber it whenever the temperature of the outer evaporator rises to a predetermined value. Liquid refrigerant is then admitted to the liquid line 88 and flows into the outer evaporator through the manifold 33. The headers 28am maintained normally partially filled with liquid refrigerant and the passages 3| and 32 communicating therewith are kept flooded with liquid refrigerbottom of the chamber 48 and is' discharged through the connection 49 with a substantial portion of the gaseous refrigerant. Some of the gaseous refrigerant flows from the chamber 48 through the rstricted passage 59 and returns directly to the suction line (9 by way of the header 36. The relative volume of liquid refrigerant in the conduit 49 is, therefore, greater than that in the conduit 41 leading to the chamber 48. The inner evaporator is maintained flooded by the continual addition thereto of liquid refrigerant flowing through the sinuous passage 4| from the connection 49 and the liquid refrigerant flows through the series conduit at a rate providing substantial freezing capacity at all times. Refrigerant is vaporized within the inner evaporator and the vaporized refrigerant collects inthe header 36 and is withdrawn therefrom through the suction line i9. When the temperatureof the outer evaporator has been reducedsufliciently, the control 20 operates to stop the compressor and thereby stops the further supply of liquid refrigerant to the float valve chamber l6.

From the foregoing, it is readily apparent that I have provided an improved arrangement for controlling the flow of refrigerant in a refrigerating machine having a plurality of evaporators arranged in series and maintained at different temperatures.

While I have described my invention in connection with a cooling unit for household refrigerating machines, other applications will readily be apparent to those skilled in the art. I do not, therefore, desire my invention to be limited to the construction shown and described,

and I intend in the accompanying claims to cover all modifications within the spirit and scope of my invention. I

This intermediate temperature is suitable for the preservation of i What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A refrigerating machine including two evaporators, means for supplying refrigerant to one of said evaporators, means for conveying liquid and gaseous v refrigerant from said one evaporator to the other of said .evaporators, said other evaporator having a series conduit for carrying refrigerant through one portion thereof, means for withdrawing gaseous refrigerant from said other evaporator, means including a restricted passage arranged in said conveying means for maintaining a difference of pressure between said evaporators, and means communieating with said conveying means between said restricted passage and said series conduit for diverting fromsaid series conduit a quantity of gaseous refrigerant.

- 2. A refrigerating machine including two evaporators, means for supplying refrigerant to one of said evaporators, means forconveying liquid and gaseous refrigerant from said one evaporator to the othrof said evaporators, means for withdrawing gaseous refrigerant from said other evaporator, means including a restricted passage arranged in said conveying means for maintaining a difference of pressure between said evaporators, and means communicating with said conveying means between said passage and said other evaporator for diverting from said other evaporator a quantity of gaseous refrigerant.

3. A refrigerating machine including two evaporators, means for supplying refrigerant to one of said evaporators, means for conveying liquid and gaseous refrigerant from said one evaporator to the other of said evaporators, means for withdrawing gaseous refrigerant from said other evaporator, means including a restricted, passage arranged in said conveying means for maintaining a difference of pressurebetween said evaporators, and means communicating with said conveying means and including a chamber arranged between said passage and. said other evaporator anda tube connecting said chamber and said withdrawing means for diverting from said other evaporator a quantity of gaseous refrigerant.

4. A refrigerating machine including two evaporators, means for supplying refrigerant to one of said evaporators, means for conveying liquid and gaseous refrigerant from said one evaporator to the other of said evaporators, means for with-- drawing gaseous refrigerant from said other evaporator, means including a restricted passage .diverting means being sufficiently restricted to maintain a substantial pressure drop across said other evaporator. a

5. A refrigerating machine including two evaporators, means for supplying refrigerant to one of said evaporators, means forconveying liquid and gaseous refrigerant from said one evaporator to the other of said evaporators, said other evaporator having a header for collecting gaseous refrigerant, means including a restricted passage arranged in said conveying means for maintaining a difference of' pressure between said evaporators, means including a tube communicating with said conveying means between said passage and said other evaporator and with said header for diverting from said conveying means a quantity of gaseous refrigerant, and means for withdrawing gaseous refrigerant from said header.

6. A refrigerating machine including two evaporators, means for supplying refrigerant to one of said evaporators, the other at least of said evaporators being of the flooded type and comprising a header and a plurality of depending refrigerant circulating conduits, means for conveying liquid and gaseous refrigerant from said one evaporator to said other evaporator and for admitting a mixture of liquid and gaseous refrigerant to said other evaporator below the normal level of liquid refrigerant therein, means for withdrawing gaseous refrigerant from said header,

means including a restricted passage arranged in said conveying means for maintaining a difference of pressure between said evaporators, and means including a tube communicating with said conveying means between said passage and said other evaporator and with said header for diverting from said other evaporator a quantity of gaseous refrigerant.

7. A refrigerating machine including two evaporators, means for supplying refrigerant to one of said evaporators, the other of said evaporators comprising a header and a plurality of flooded depending refrigerant circulating conduits and a series conduit for carrying refrigerant through a portion of said other evaporator and for conveying refrigerant to said flooded conduits, means for conveying liquid and gaseous refrigerant from said one evaporator to said series conduit, means for withdrawing gaseous refrigerant from said header, means including a restricted passage arranged in said conveying means for maintaining a difference of pressure between said evaporators, and means including a tube communicating with said conveying means between said passage and said series conduit and with said header for diverting from said series conduit a quantity of gaseous refrigerant.

8. A refrigerating machine including a cooling unit comprising two evaporators one arranged within the other, means for supplying refrigerant to the outer one of said evaporators, the inner one at least of said evaporators being of the flooded type and having a header and a plurality of depending refrigerant circulating conduits, means for conveying liquid and gaseous refrigerant from said outer evaporator to said inner evaporator and for admitting said liquid and gaseous refrigerant to said inner evaporator below the normal level of liquid refrigerant therein, means including a restricted passage arranged in said conveying means for maintaining a difference of pressure between said evaporators, means including a tube communicating with said conveying means between said passage and said inner evaporator and with said header for diverting from said conveying means a quantity of gaseous refrigerant, and means for withdrawing gaseous refrigerant from said header.

9. A refrigerating machine including two evaporators, means for supplying refrigerant to one of said evaporators, an outlet connection for removing liquid and gaseous refrigerant from said one evaporator, an upright cylindrical vessel communicating with said outlet connection, means including a connection communicating with said vessel near the bottom thereof and with the other of said evaporators for conveying liquid and gaseous refrigerant to said other evaporator, means including a restricted passage arranged in said outlet connection for maintaining a difference of pressure between said evaporators, means including a tube communicating with the upper end of said vessel for diverting from said other evaporator a quantity of gaseous refrigerant, and means for withdrawing gaseous refrigerant from said other evaporator and from said tube.

10. A refrigerating machine including two evaporators, means for supplying refrigerant to one of said evaporators, an outlet connection for removing liquid and gaseous refrigerant from said one evaporator, an upright cylindrical vesselcommunicating with said outlet connection, means including a connection communicating with said vessel near the bottom thereof and with the other of said evaporators for conveying liquid and gaseous refrigerant to said other evaporator, means including an adjustable valve arranged in said outlet connection for maintaining said evaporators at different pressures and for selecting the differential of pressures between said evaporators,

means for maintaining said valve partially open at all times, means including a tube communicating with the upper end of said vessel for diverting from said other evaporator a quantity of gaseous refrigerant, and means for withdrawing gaseous refrigerant from said other evaporator and from said tube.

LEONARD W. ATCHISON. 

